John ashcroft



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JOHN A-SHGROFT, OF NEW YO RK,N. Y.

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TO ALL WHOM IT MAY CONOERN;

Y Be it known that I, Jouir Asncnosr, of the city, county, and State of New Yorin-have invented a new and useful Improvement in 'Safety-Valves for the boilers-of locomotives and other steam-engines; and do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the aecompanying drawings, making part ofthe specification, ol which- Figure I represents a vertical section of said safety-valve and its enclosing-case, and

Figure 2 a horizontal section ofthe valve. 4 A

The nature of my invention consists in the construction of a safety-valve and its seat for steam-generators, andin the arrangement of the same,.and of the dome and case,`so that the steam shall' be at all times in direct communication with the face of the valve, by means cfa circular opening in the valve-seat, into which steam is admitted through inlet-openings in the steam-chamber ofthe seat.

Having described the nature of my invention, I Will now describe its construction and operation. In the drawings" A represents a small steam-dome, attached to a boiler, which sustains the metallic valve-case B, (the ordinarymechanism for holding the valve on its seat,) consisting of astand, C, fulcrnm,vD, weighted leven-E,

and the valve-seat E, which is screwed into the top of the dome, at G, as shown in the drawings.

The valve-seat has a circumscribing steam-chamber, H, into ,which the steam from' the boilerenters through openings, I I, die., and has also a circular opening, K, which forms a double seat, ZZ, for the valve, and by means of which the face of the valve is exposed to the action of the steam, (see iig` 1,) and L is the guidechamher, having valve-guides, m m, between which the steam escapes as the valve is raised.

M is the valve, resting on the circular opening K, or double seat Z Z.

O isthe spindle, and Y i u P is the open body ofthe valve,for exit ofthe steam as the valve is raised from its seat.

The operation of my invention is as follows: I

The dornelA'being attached to the boilertof a steam-engine, as shown, v"the steam entering the openings I I.

in t'ne chamber H, nillpress'through the circular 'opening K,'and against the exposed face of thevalve M.

Now, as the force exerted by the steam on the valve exceeds the working pressure, the valve M will be raised from its seat or bearings, Z Z, and the'surplus steam permitted to escape from the boiler through the open body P of the valve, as well as through the open guide-chamber L ofthe valve-seat, by means of which the pressure ofthe steam is immediately regulated, and accident from explosion less liable.

I am aware oi' the patent 0f S. B. Dougherty, assigner to himself` and John Ashcroft, and dated March 10, 1868, for improvement in safety-valves. My present invention is intended as an improvement on said patent, I replacing his two seats by one, a double-cone seat,- where the expansion and contraction are moreequahand the valve can keep a better seat, besides being cheaper or" construction, dto.

Having described my invention, what I claim, and desire to secure by'Letters Patent, is-

1. rlhe construction of the valve M, and its seat, Il', with guides, m, and openings.I I, as herein set forth.

2. The arrangement of the dome A, case B, and valve-seat F, as herein set forth.

In testimony whereof, I have hereunto set my signature, this 22d day of July, A. D.'1868.`

. JOHN ASHCROFT.

Witnesses:

A. NEILL', T. E. Pit'nrrrnes. 

